This study investigates mediation by macromolecules and filipodia of the interaction between foreign surfaces and blood. Adhesion to selected substrates is studied by a centrifugal test with and without induced platelet shape change in normal and modified plasmas using several anticoagulants. The observations are extended to native whole blood flowing over the substrates in the form of special bead columns. A variety of measures of blood reactivity and composition are performed sequentially. Some findings to date are: 1) The number of rabbit platelets adherent to "clean" (freshly annealed) glass is about 5% of the amount (5 x 10 to the 6th power/cm2) for siliconized glass. 2) The force needed to detach a platelet is about one microdyne parallel to or away from a siliconized surface. 3) The zeta-potential/pH profiles of "clean" and siliconized glass become similar after exposure to "hard spun" platelet-free citrated plasma. 4) Under conditions whereby platelet retention from native whole blood is complete for both conventional glass bead columns and siliconized equivalents, retention by "clean" (barely fused) glass bead columns is minimal. 5) The platelets in the effluent from these fused glass bead columns exhibit normal retention when passed through a conventional head column.